Microsomal HMG-CoA reductase and cholesterol 7 alpha-hydroxylase, the rate controlling enzymes for cholesterol and bile acid synthesis respectively, will be assayed in microsomal membranes and Golgi apparatus of normal liver, transplantable hepatomas, and AAF induced hyperplastic nodules and primary hepatomas under conditions where the production of bile acid and/or cholesterol are varied. The uptake and intracellular distribution of absorbed cholesterol and cholesterol esters will also be studied. Since the enzymes' activities reflect the flux of metabolites for bile acid and cholesterol synthesis and since both are closely related processes a structural-functional correlation of this type might provide insight into how cholesterol is channeled into its several secretory and excretory pathways. A disorder in the control of uptake, intracellular distribution, or synthesis of cholasterol and its metabolic products, might help to explain the loss of cholesterol mediated "feedback control" of cholesterol synthesis that is a universal phenomenon in all hepatocellular carcinomas.